One of Somalia's most popular comedians, known for his parodies of Islamist militants, has been shot dead in the capital, Mogadishu.

Abdi Jeylani Marshale was reportedly killed shortly after leaving a local radio station where he worked as a drama producer and performer.

It is not known who carried out the murder but last year Marshale was threatened by the extremist group al-Shabaab, prompting him to go into hiding in neighbouring Somaliland for several days.

Witnesses told the BBC that Marshale was shot several times in the head and chest by two men armed with pistols. The gunmen have not been caught.

Yusuf Keynan, a presenter at Kulmiye Radio, where Marshale worked, was quoted in media reports as saying: "He had not done anything wrong to anybody, as far as we are concerned, but they shot him in the head and shoulders. This is a black day for the entire entertainment industry. He was a leader in Somalia comedy and everybody liked his performance."

Kulmiye Radio reported that hundreds of journalists, relatives, supporters and dignitaries attended his funeral. The site quoted the station owner, Osman Abdullah Guure, as urging journalists to carry guns to protect themselves: "I strongly encourage the journalists to take their guns and not consider any one protecting them; it is time to defend ourselves."

Marshale also worked for Universal TV, a London-based Somali satellite TV station. Another Universal employee, reporter and anchor Abdulkadir Omar Abdulle, survived a shooting on Saturday, according to the Committee to Protect Journalists, which says six journalists have been killed in the Horn of Africa country this year.

On Wednesday Somali security forces shot dead a would-be suicide bomber who tried to attack the venue of a national conference on a draft constitution, while a second attacker blew himself up, injuring six officers, police said.

"The two bombers wore government uniform. Six policemen were injured," Colonel Mohamed Ali, a police officer, told Reuters.

"One jumped over a wall opposite the conference building but he was shot dead outside the gate. Then another bomber jumped from another wall and his bomb exploded where government soldiers stood."

The gathering overwhelmingly backed a new constitution, paving the way for a new government to be elected this month under a UN-backed plan.

Of the 645 members of the constituent assembly present, 621 backed the document, 13 voted against and 11 abstained.

The constitutional affairs minister, Abdirahman Hosh Jabril, said: "This is an historic day – today we have witnessed the completion of a task that has been worked on for the last eight years."

African Union troops and the UN-backed government have forced al-Shabaab out of Mogadishu but the al-Qaida-linked group frequently stages attacks in the city. It still controls many areas of southern and central Somalia.

The country has been without a functioning national government since 1991.